OBD-II Generic Error Code P2406: How to Fix It

Q: Can I drive my car with a P2406 code?

Yes, P2406 is a medium-severity code and your vehicle will typically remain drivable. However, an unresolved EVAP fault can cause you to fail an emissions inspection, and in some cases a faulty leak detection pump can mask real fuel vapor leaks. It is best to address the issue within a few weeks to avoid potential emissions test failure or worsening of related components.

Q: What is the most common cause of P2406?

The most common causes are a failed or seized EVAP leak detection pump, a short to voltage in the pump's sense wire, corroded electrical connectors at the pump, or a clogged pump inlet filter. Wiring issues are particularly common on older vehicles where the harness has been exposed to heat and moisture over many years.

Q: Will P2406 cause my check engine light to come on?

Yes. P2406 is an emissions-related OBD-II trouble code and will illuminate the check engine (MIL) light on your dashboard. The light will remain on until the fault is repaired and the code is cleared with an OBD2 scanner, followed by a successful EVAP system monitor completion.

Q: How much does it cost to fix a P2406 code at a shop?

Repair costs vary by vehicle and region. If the fix is simply cleaning a corroded connector or replacing a clogged pump filter, costs may be under $50 in parts. If the full leak detection pump needs replacement, parts typically range from $50 to $250 depending on the vehicle, plus 1-2 hours of labor at $100-$150 per hour. Complex wiring repairs or ECU diagnosis can push total costs higher.

Q: Is P2406 the same as a fuel evap leak (P0442 or P0455)?

No. P2406 specifically refers to an electrical fault — a high voltage reading — in the leak detection pump sense circuit. It does not confirm there is an actual fuel vapor leak. Codes like P0442 (small EVAP leak) or P0455 (large EVAP leak) indicate the system found a physical vapor leak. However, a faulty leak detection pump caused by P2406 can prevent the system from running its leak test, so it is possible to have both electrical and leak-related EVAP codes at the same time.

Abstract

Error code P2406 indicates that your vehicle's onboard diagnostic system has detected an abnormally high voltage signal in the EVAP (evaporative emission control) leak detection pump sense circuit. This pump is responsible for pressurizing the fuel vapor system so the car's computer can check for fuel vapor leaks that could harm air quality. When the sense circuit reads a voltage higher than expected, it typically points to a wiring fault, a failed leak detection pump, or a blocked or damaged EVAP component.